These Giant, Vest-Wearing Sniffer Rats Could Help Combat the Illegal Wildlife Trade, Scientists Say

Poachers and wildlife traffickers go to great lengths to disguise their contraband products so they can smuggle them out of a country. They’ll paint ivory tusks black, or coat them in chocolate and wrap them in candy bar-like packaging. They’ll hide pangolin scales in boxes of cashews, or create containers with false walls and hidden compartments. They’ll smother their illegal goods in smelly materials to try to confuse sniffer dogs.

But law enforcement officials may soon have a new tool for combatting these and other tactics: rats.

Scientists are training African giant pouched rats (Cricetomys ansorgei) to sniff out pangolin scales, rhino horns, elephant tusks and African blackwood being transported illegally. These clever critters have not only learned how to identify the contraband items, but they’ve also figured out how to alert their handlers: They use their front paws to tug on a little ball attached to a custom, red neoprene vest they wear when working, which triggers a beeping sound.

Researchers described the skills of these vest-wearing, sniffer rodents in a new paper published Tuesday in the journal Frontiers in Conservation Science.

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The African giant pouched rat is the world’s largest rat, weighing three pounds on average and stretching some two to three feet long, from the nose to the tip of the tail. The nocturnal rodents live in sub-Saharan Africa and earn their name from the pouches in their cheeks, which they use to store food. Importantly, these rodents have a keen sense of smell, and they’re quick learners.

In the past, scientists with the Tanzania-based nonprofit APOPO have trained African giant pouched rats to detect tuberculosis, find land mines and locate earthquake survivors. More recently, the team turned its attention to fighting the illegal wildlife trade.

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For the new study, researchers worked with 11 rats named Kirsty, Marty, Attenborough, Irwin, Betty, Teddy, Ivory, Ebony, Desmond, Thoreau and Fossey. Using food as a reward, the team first taught the rodents how to stick their snouts into a hole where they’d be exposed to scent samples, a behavior called a “nose poke.”

Once the furry participants had mastered this skill, the researchers then began introducing the rats to four commonly smuggled items, as well as objects that are often used to mask the smell of these illicit products.

The target odors were pangolin scales, rhino horns, elephant tusks and African blackwood, a tree that is often used to make musical instruments. The non-target odors were things like coffee beans, washing powder or electrical cables. In total, eight of the rats completed the training and learned how to differentiate between the four target and 146 non-target smells.

When the scientists tested the rodents five and eight months later, they still remembered the smells they had been taught.

If the trained rats become “employed,” so to speak, they could one day help curb a major global problem. The illegal wildlife trade is worth an estimated $7 billion to $23 billion per year, per a report from the United Nations Environment Program and Interpol. It’s now the fourth-largest illegal trade industry, behind narcotics, human trafficking and counterfeit products, according to U.S. Immigration and Customs Enforcement.

“Wildlife is deemed to be a low-risk commodity,” says Crawford Allan, who serves as vice president of nature crimes and policy advocacy for the World Wildlife Fund and was not involved in the sniffer rat research, to CNN’s Alex Rodway. “Unfortunately, organized crime knows there’s a real weak spot in detection methods of ports, seaports and airports, particularly in Africa.”

Once the sniffer rats had mastered their contraband-detecting behaviors in a laboratory setting, researchers took them out into the real world for a trial run. Last year, they headed to the seaport of Dar es Salaam in Tanzania, a major hub for international trade, per CNN. The rodents successfully found more than 83 percent of planted targets—even when the targets were masked by other scents.

African giant pouched rats likely won’t replace sniffer dogs—but, rather, they may eventually be used to complement the trained canines. Rats are smaller and nimbler than dogs, which gives them an advantage when it comes to exploring small nooks and crannies.

“You could envision detection dogs screening vast open areas or tracking poachers while rats screen container contents or specific packages,” says study co-author Kate Webb, a neuroscientist at Duke University, to the Australian Broadcasting Corporation’s Hannah Murphy.

Rats are also cheaper to transport and maintain than dogs are, and they have no problem working with different human handlers. They also tend to be quick and easy to train, and they live a long time—potentially up to 11 years—so the return on investment is high.

The rats’ relative affordability is an especially big perk, because smugglers are often trafficking wildlife products from poorer countries.

“Existing screening tools are expensive and time intensive, and there is an urgent need to increase cargo screening,” says study co-author Isabelle Szott, a behavioral ecologist who trained the rats at APOPO but now works at the Okeanos Foundation in Germany, in a statement. “APOPO’s rats are cost-efficient scent detection tools. They can easily access tight spaces like cargo in packed shipping containers or be lifted up high to screen the ventilation systems of sealed containers.”

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Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.